The weaver rails are universal, ive never herd of the different sized weavers. The MR4 has picitanny rails on it thou which should be able to mount any wever rail device. If it had weaver rails THEN you would have to pay attention to what you bought cuz a picitanny device can not mount to weaver rail.

I dont like m16 handles, i seen them way to often with being a service member, but the only make so many options and i dont machine stuff so my options are very limited.

And ANSgear i think they just stopped selling them because no-one was buying them. I has to special order my mr4 at my local shop. They are still very new, ant the mr1,2,3 are "proven" to work. And after looking for an MR2 for a while, at fields and shops thier considered a rare treasure especially if they have eyes. Kingman is just not as popular as when i first started with my imagine 5-6 years ago. I've let people shoot my spyders before and they are always surprised at how well the can perform. Its just not a common fact, people prefer tipps, cockers, whatever is the flavor of the month. Hell at my current field i see more angles then anything.(besides rentals, always tons of those). Spyders have been cursed, being labled as low-end. when thier just as good as many other markers out there.